The present invention relates to catheters and more particularly to catheters used for introduction and removal of fluids from a body.
Multi-lumen catheters are used for a variety of applications where it is necessary to have two or more separate fluid pathways. One such application for a multi-lumen catheter is for use in hemodialysis. During hemodialysis, a dual-lumen catheter can be employed to simultaneously accommodate opposing blood flow. More specifically, one lumen aspirates blood from a blood vessel of a patient to a dialysis machine where it is processed for the removal of toxins, while the other lumen infuses the purified blood to the patient.
The primary problem in many dialysis catheters is that related to clotting and fibrin sheath formation. Thrombus and fibrin can occlude distal tips of the catheter lumens, resulting in loss of catheter function when such an occlusion prevents blood flow. This typically occurs initially in the arterial lumen used for aspiration of blood from a patient. A secondary problem is that related to the arterial lumen xe2x80x9csuckingxe2x80x9d against the vessel wall in which it resides. This problem can occur if the arterial lumen ports become fully occluded by the patient""s vasculature. When either of the aforementioned problems is observed clinically, the first attempt at salvaging the catheter is to reverse the bloodlines (i.e., to aspirate through the longer lumen, and to infuse through the shorter lumen, contrary to normal blood flow). While such a scenario causes cleaned blood to flow directly toward the lumen that is under vacuum, line reversal in certain catheters can result in inefficient flow (high re-circulation).
Accordingly, an object of the present invention is to provide a dialysis catheter with adequate profile to allow efficient exchange of blood, while preventing problems associated with occlusion. Another object of the present invention is to provide a dialysis catheter with a moveable lumen so that post-placement adjustment is possible. Further objects and advantages of the present invention will become apparent from the ensuing description and drawings.
In accordance with the present invention, a split tip dialysis catheter comprises an outer tube and an inner tube, wherein the two tubes can be arranged over at least a portion of their length in a coaxial configuration. The inner tube may be connected to the outer tube along a proximal segment, secured at the distal end of the outer tube, or both, but generally the inner tube will remain free to move relative to the outer tube to optimize functionality. In addition, the inner tube can be arranged to be removable from the catheter for replacement thereof. The inner and outer tubes can also be configured to have a differing geometry along their length.
What is claimed is a multi-lumen catheter comprising an outer tube comprising a tip portion, a body portion and a port, wherein the body portion comprises a first lumen, and wherein the tip portion comprises a second lumen in fluid communication with the first lumen, and an inner tube disposed within the body portion of the outer tube along at least a portion of its length, comprising a third lumen, wherein the position of a distal end of the inner tube relative to the port is variable.